Piezoelectric crystal and condenser combination



y 1950 w. E. KUENSTLER 2,508,720

PIEZOELECTRIC CRYSTAL AND CONDENSER COMBINATION Filed April 16, 1.947

INVENTOR.

fl alZerE Jtuwzier Patented May 23, 1950 PIEZOELECTRIC CRYSTAL AND CON-DENSER COMBINATION Walter E. Kuenstler, Clifiside Park, N. J.

Application April 16, 1947, Serial No. 741,835

8 Claims. 1 This invention has relation to piezo-electric crystals andmore particularly to the manner in .which the crystals are mounted andenclosed and are combined with a condenser.

At the present time, in many electrical or radio circuits in which apiezc-electric crystal is incorporated a fixed condenser is occasionallyinterposed between one of the electrodes of the crystal and an adjacentvacuum tube, while the second electrode of the crystal is sometimesconnected to a resistor which is grounded to the metal chassis or baseof the instrument. I have .found that the set can be rendered more com-.pact and the wiring of the same simplified considerably if thecondenser can be combined with the crystal assembly and be housedtherewith in 'a single container. Hence, the primary object of thepresent invention is to provide means by which a condenser andpiezo-electric crystal can be combined in a single unit, with a portionof 'the container or housing in which the condenser and crystal arecontained possibly serving as a "resistance between one of theelectrodes of the crystal and the chassis-grounded potential,

In the accompanying drawing, wherein an illustrative embodiment of theinvention is diswclosed, Fig. 1 is a side elevation of a combinedcrystal and condenser and the container therefor; Fig. 2 is a sectionalview taken on the line 22 of Fig. 1, looking in the direction of thearrows; Fig. 3 is a sectional view on the line 3-3 of Fig. 2, looking inthe direction of the arrows; Fig. 4 is a sectional view taken on theline l4 of Fig. 2 locking in the direction of arrows.

Referring to the drawing, l indicates the base portion of the crystalholder, said base consisting of an annular section of insulatingmaterial formed with a continuous shoulder 2 constituting a seat for thesupport of the crystal 3 of the quartz or other piezo-electric material.ihe crystal 3 is sandwiched between a pair of metallic electrodes, shownat 4 and 5 in the known manner, the lower electrode 4 bein supportedupon the seat 2. The crystal assembly, consisting of the crystal 3 andthe two electrodes 4 and by a metallic casing 8 which has its circumfer-"ential wall 9 telescoping with the wall of the me- .f tallic covermember I, and the overlapped portions of the Wall 8 and the cover memberI are soldered together to thus provide a sealed container for thecrystal and other parts.

. Extending from the container body 8 is a tubular extension l0constituting the stem or plug portion of the device, said extensionenclosing a body of insulating material II which protrudes out of thetubular extension Ill, as indicated at l2, the end of the tubularextension It being in the form of an inturned flange embedded in theinsulating material, as indicated at I3. Passing axially through theinsulating material II is a tubular metallic stem or pin [4 whichterminates at its outer end in a rounded head IS and is provided at itsinner end with a disk-shaped plate l5 of metal or conducting material,said plate l5 constituting one of the plates of a condenser. Plate ordisk I5 is located in the central aperture ll of the insulating base Iand it is spaced from the electrode 4', so that the plate or .disk l5will constitute one plate of a condenser,

and the electrode 4 will constitute the second plate thereof, the twoplates being separated by a suitable air space forming a dielectric inthe known manner. The spacing of the condenser plate l5 from theelectrode 4, its thickness and area relative to the electrode 4, may, ofcourse, be regulated to secure the required condenser capacity and noeffort is made herein to show the correct relative spacing andproportions of these parts since the same are to be varied, as abovestated, to obtain the required results for any particular installation.

In the form shown, the condenser plate I5 is disclosed as being fixedlysecured on the end of the stem l4, but it will be obvious thatadjustable arrangement might be had whereby, during assembly of thedescribed structure, the plate I5 of the condenser, consisting of theelectrode 4, 40'

example, the plate or disk l5 might be threadably to secure the requiredcondenser capacity. For

mounted on the end of the stem or pin [4- and be thus adjustable thereonto enable it to be situated at the precise distance required from theelectrode 4. Also, in herein describing the electrodes 4 and 5, I haveindicated that the same may be metallic plates between which the cry-.stal 3 is sandwiched. As an alternative for such capable offunctioningas a condenser plate in the manner herein described. In theuse of the improved crystal and condenser assembly, the same is placedin the circuit by the insertion of the stem portion I0, I i into astandard bayonet-type socket, which engages the radially extending pinsII and I 8, to hold the device in the socket in the known manner. Thehead I 6 at the end of the stem I4 establishes contact with the centralcontact spring of the socket, thus placing the condenser, consisting ofthe plate [5 and co-operating plate 4 (the crystal electrode) in thecircuit. At the same time, the sleeve contacts with the shell of thesocket, thus closing circuit between the same and upper electrode 5 ofthe crystal. Thus, the eilect secured in a circuit is that of a fixedcondenser interposed between one of the electrodes of the crystal and anadjacent tube element to which the condenser might be connected. At thesame time, the effect of a resistor is obtained between the secondelectrode of the crystal and chassis-grounded potential, since the metalcasing consisting of the electrically connected parts I, 8 and I0, areinterposed between the electrode 5 and the chassis and might be employedas a substitute for the conventional resistor.

From the foregoing, it will be clear that I have provided a constructionof simple and effective form wherein a crystal and a condenser areunitarily housed, with a portion of the crystal assembly serving as oneof the plates of the condenser, so that simplicity in wiring andconservation of space is had, and other advantages secured, as will bereadily apparent to those skilled in this art.

What I claim is:

1. A crystal mounting comprising, a support of insulating material, apair of electrodes, a crystal interposed between the same, means forholding the crystal and electrodes on the support, a stem of insulatingmaterial extending from the support, a metallic pin extending throughthe stem, one end of the pin terminating near one of the electrodes, anda plate carried by said end of the pin and located near but spaced fromthe electrode whereby said plate and electrode co-operate to form acondenser.

2. In a crystal mounting, an insulating support including a seat, acrystal and electrodes held on said seat, a plug portion extending fromthe support, a metallic enclosure for the support and plug, a metalcover fitted over and secured to the enclosure, a spring interposedbetween the cover and one of the electrodes, a pin extending through theplug, said pin having a head at one end of the plug and having a disk atits opposite end, the disk being located within the support and adjacentto and spaced from one of the electrodes whereby said disk and saidelectrode cooperate to form a condenser.

3. In a crystal mounting, a seat upon which a crystal and electrodes aresupported, a stem of insulating material extending from the seat, ametal shell surrounding the seat and a substantial part of the stem, acover member fitted over and enclosing the top of the shell, a springinterposed between said cover member and one of the electrodes tothereby urge the crystal and electrodes toward the seat, a in extendingthrough the stem and exposed at one end of the same, the opposite end ofthe pin carrying a disk spaced from and extending substantially parallelto one of the electrodes whereby said electrode constitutes one of, theplates of a condenser and the disl; constitutes the second plate of thecondenser.

4. In a crystal mounting, a metallic housing, a seat of insulatingmaterial located within the housing, a crystal and electrodes supportedon said seat, means for resiliently urging the crystal and electrodestoward the seat, said means establishing electrical connection betweenthe housing and the first of the electrodes, the housing including aplug extension containing insulating material, a pin extending throughsaid insulating material and carrying a condenser plate at one end, saidplate being located adjacent to the second one of the electrodes,whereby said second electrode serves as a second condenser plate.

5. In a crystal mounting, a housing enclosing a crystal having electrodeportions, a condenser plate within the housing located adjacent to oneof the electrode portions whereby said electrode portion will act as thesecond plate of the condenser, the condenser plate having a terminallocated externally of the housing and insulated from the same, and thesecond electrode portion of the crystal being electrically connected tothe housing, said housing having a plug extension for fitment in asocket.

6. In a crystal mounting, a metallic housing, an annular seat of insulatng material located within the housing, a crystal and electrodessupported on said seat, spring means for resiliently urging the crystaland electrodes toward the seat, said spring means establishingelectrical connection between the housing and the first of theelectrodes, the housing including a tubular metal plug extension contaning insulating material, a pin extending axially through saidinsulating material and carrying a disk-like condenser plate at one end,said plate being located adjacent to the second of the electrodes,whereby said second electrode serves as a second condenser plate, saidpin having an end located at the end of the insulating material andspaced from the metal plug extension.

7. In a crystal mounting, a metal housing having a plug portion, acrystal and electrodes contained in the housing, one of the electrodesbeing electrically connected to the housing whereby the housing servesas a resistor, a condenser plate in the housing and insulated therefromand spaced from the second electrode, the latter electrode serving as asecond condenser plate, and an extension from the condenser plate,extend ng through the plug and terminating in a contact member.

8, A crystal mounting comprising, a metallic housin a support ofinsulating material, a pair of electrodes, a crystal. interposed betweenthe electrodes, means for hold ng the crystal and electrodes in thesupport, a metallic pin insulated from the metallic housing, one end ofthe pin terminating near one of the electrodes, and a plate carried bysaid end of the pin and located near but spaced from. the electrodewhereb said plate and said electrode co-operate to form a condenser.

WALTER E. KUENSTLER.

The follow ng references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,768,888 Coleman et al. July 1,1930 2,069,633 Tripp Feb. 2, 1937 2,157,665 Hollman May 9, 19392,284,545 Usselman May 26, 1942 2,390,048 Bach Dec. 4, 1945 2,429,414Kuenstler Oct. 21, 1947

